1. Field of the Invention
The present invention relates to a method for forming a conductive film pattern used for an electronic circuit or an integrated circuit, an electro-optical device produced using this method for forming a conductive film pattern, and an electronic apparatus having the electro-optical device.
2. Description of Related Art
As a conventional method for forming a conductive film pattern used for wiring, a method of forming a metal thin film on the entire surface of a substrate using sputtering, vapor deposition, or the like, and etching the undesired portions using photolithography in order to form a desired conductive film pattern, is the most general method. However, this method has complex processes, requires an expensive vacuum apparatus, and since the material usage efficiency is a few percent, almost all the material is discarded. Therefore, an easier method with a lower cost than the conventional method has been required.
On the other hand, U.S. Pat. No. 5,132,248 suggests a method of direct pattern application of a liquid in which fine particles are dispersed onto a substrate using an ink jet method and then converting into a conductive film pattern by heat treatment or laser irradiation. According to the above method, photolithography is not required and processes become much easier. Such patterning using an ink jet method has merits of having simple processes and the amount of raw materials to be used is small; however, if a bank (to be explained below) is not used, it is limited to forming a pattern having a size of approximately 100 xcexcm with a positioning accuracy of approximately 30 xcexcm. In order to improve the processing accuracy using the ink jet method, as disclosed in Japanese Unexamined Patent Application, First Publication, No. Sho 59-75205, a method is used which controls the location of droplets which are jetted out by providing a bank on a substrate. If the bank is used, without discharging droplets, which are jetted out onto the substrate, out of the bank, and a pattern of approximately 30 xcexcm can be formed with a positioning accuracy of approximately 1 xcexcm. However, such a bank requires forming by the use photolithography, and therefore, its cost becomes high.
Furthermore, in order to apply this to LSI and the like, a method for spin-coating a solution in which copper particles are dispersed in a solvent onto a substrate has been suggested in recent years (Hirohiko Murakami, et al., Preliminary Report No. 2 of the Spring 1999, 46th Japan Society of Applied Physics Academic Lecture Meeting, page 29, ZQ-15). When this method is used, a pattern of a copper thin film is obtained by pouring the solution into trenches and holes prepared on the substrate, and drying and heating the substrate. However, to form the trenches and holes, it is required to use photolithography.
As described above, when a conductive film pattern is formed by forming a film from a liquid material and patterning the film, so far, there has been no patterning means which has an accuracy on the order of microns, and which obtains a conductive film pattern by a simple process without using photolithography.
In a method for forming a conductive film pattern by pattern applying a solution comprising fine particles onto a substrate, the present invention provides a method for forming a conductive film pattern with high accuracy and simple processes by, selectively applying a liquid material to only lyophilic regions on the substrate on which patterns of lyophobic regions and lyophilic regions are formed using an organic molecular film, and then converting the liquid material applied onto the lyophilic regions into a conductive film pattern by heat treatment, without controlling the location of droplets in a bank or a trench formed by photolithography as is done in the a conventional method.
In order to solve the above problems, the present inventors have diligently carried out research and have found that by a method for forming a conductive film pattern, comprising the steps of: forming a predetermined pattern comprising a lyophilic region and a lyophobic region using an organic molecular film on a substrate surfaces; selectively applying a solution comprising conductive fine particles to the lyophilic region on the substrate; and converting the applied film of the solution into a conductive film by a heat treatment, it is possible to form an accurate conductive film with an easy process.
According to the present invention, photolithography and etching steps such as development, rinsing, and the like are not required, and it is possible to provide a patterning technique for conductive films having an accuracy on the order of microns by simple process.